Create a base class for assemblers.

This base class defines an interface that assemblers must adhere to.
For now, we use it to hold the code buffer.

Change-Id: I487430bb98c7044e57b348cffa1e74a2a4c8026f
diff --git a/src/assembler-base-vixl.h b/src/assembler-base-vixl.h
new file mode 100644
index 0000000..528627d
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+++ b/src/assembler-base-vixl.h
@@ -0,0 +1,52 @@
+// Copyright 2016, VIXL authors
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+//   * Redistributions of source code must retain the above copyright notice,
+//     this list of conditions and the following disclaimer.
+//   * Redistributions in binary form must reproduce the above copyright notice,
+//     this list of conditions and the following disclaimer in the documentation
+//     and/or other materials provided with the distribution.
+//   * Neither the name of ARM Limited nor the names of its contributors may be
+//     used to endorse or promote products derived from this software without
+//     specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
+// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
+// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef VIXL_ASSEMBLER_BASE_H
+#define VIXL_ASSEMBLER_BASE_H
+
+#include "code-buffer-vixl.h"
+
+namespace vixl {
+namespace internal {
+
+class AssemblerBase {
+ public:
+  AssemblerBase() {}
+  explicit AssemblerBase(size_t capacity) : buffer_(capacity) {}
+  AssemblerBase(byte* buffer, size_t capacity) : buffer_(buffer, capacity) {}
+
+  CodeBuffer* GetBuffer() { return &buffer_; }
+  const CodeBuffer& GetBuffer() const { return buffer_; }
+
+ protected:
+  // Buffer where the code is emitted.
+  CodeBuffer buffer_;
+};
+
+}  // namespace internal
+}  // namespace vixl
+
+#endif  // VIXL_ASSEMBLER_BASE_H